Radiation generating and transmitting device



1959 D. M. GOODMAN 2,915,659

RADIATION GENERATING AND TRANSMITTING DEVICE Filed Jan. 14, 1957 FIG 3 FIG 2 FIG 5 INVENTOR. David M. Goodman Unite RADIATION GENERATING AND TRANSMITTING DEVICE This invention relates to cathode ray or directed ray tubes containing electro-magnetic radiation manipulating means for the purposes, inter alia, of controlling or generating signals. In particular this invention is directed to a cathode ray tube capable of being used as a display device in a Plan Position Indicator and capable also of furnishing displays in a plurality of colors.

Among the features of this invention is the combination of a cathode ray tube with means inside the tube that pick up and convey an electromagnetic indexing signal, generated at the face of a cathode ray tube, to means outside the tube for processing or using the signal.

Another feature of this invention is that the means that gather and transmit such indexing radiation may be combined with, or may constitute part of, the structure that supports elements or electrodes of the gun of the cathode ray tube. The radiation transmitting means may be a rodlike structure of quartz, fused silica, or other suitable material; and may consist of one or more sections.

Known devices and techniques that use index signals, which generally are generated to indicate the position of an'electron beam at the face of a cathode ray tube, exhibit an excessive time delay in information transmission or use ineflicient and cumbersome means to achieve such transmission. When electro-rnagnetic radiation is used in the transmission loop or path, the practice has been to position detection devices outside of the cathode ray tube envelope. Improvement in overall performance results from positioning the detector within the cathode ray tube envelope, but such positioning of the detector may create an awkward mechanical arrangement of components.

Accordingly one of the objects of this invention is to provide inside a cathode ray tube exceedingly simple and tes Patent ice from following the detailed description of the invention eflicient means for conveying or guiding electro-magnetic radiation from the inside of the cathode ray tube envelope to a suitable detector located outside of said cathode ray tube.

Another object is to provide within a tube or housing simple and eflicient means for conveying or guiding or transmitting electro-magnetic radiation, that originates Withinthe tube or housing as a result of or upon bombardment by a 'focussed beam of energy, to detection means external of said tube or housing.

Another object of this invention is to provide electrically insulating components, that support elements or electrodes of the electron gun and also serve as a guide or guides for the 'electro-magnetic radiation being transmitted to the detecting means.

Another object of this invention is to provide means that allows for separate assembly of the structure that comprises the electro-magnetic transmission means.

Another object of this invention is to provide means which allow relative mechanical motion between the means which convey the electro-magnetic radiation and the tube envelope.

Still another object of this invention -is to provide means for filtering electronic signals in the time and amplitude domains by presenting the signals on the face of a display taken in conjunction with the accompanying drawing, wherein:

Figure 1 is a diagrammatic cross-sectional view of a display device in the form of a cathode ray tube in accordance with features of the invention which employs magnetic deflecting means, a conventional electron gun, and a special radiation collector and transmitter in combination with a selective filter and means for converting the transmitted electro-magnetic radiation into electrical signals.

:Figure 2 is a diagrammatic illustration of the face of the cathode ray tube of Figure 1 showing, groups of rings of radiation emitting material deposited thereon.

Figure '3' illustrates, on an enlarged scale, a section of the structure of Figure 2.

Figure 4 is an end (rear) view of the cathode ray tube of Figure 1.

Figure 5 illustrates a portion of an electron gun structure embodying features of this invention.

Referring to Figure 1, a cathode ray tube envelope 11, houses an electron gun'13. Conventional electro-magnetic deflecting means are indicated at 1 5, and a high voltage accurately aligning the header with the special socket into which the tube is inserted.

Electro-magnetic radiation transmitting means .28 is a rod or bar of transparent fused silica or other material such as a suitable glass. It may also be in the form of a hollow cylindrical pipe. When in the solid form, a sub stantially hemi-spherical termination is preferred at 25, An appreciable portion of the electro-magnetic radiation generated upon the inside face of 19 impinges upon surface 25. This radiation is then transmitted by means of complete internal reflection along 28. Details regarding the process of internal reflection, and details concerning the positions at which 25 may be located in the tube is contained in my co-pending application, Serial #522,609, filed July 18, 1955.

A vacuum seal between 28 and the cathode ray tube envelope is illustrated at 26, made in accordance with known principles and techniques. Means 29 designates a photo-multiplier or other device for converting the radi: ation transmitted to it through 28 into electrical signals. Filter 27, when used, controls the passage of radiation from 28 to 29. Preferably, filter 27 passes only that electro-magnetic radiation which is used for index signal generation. Spurious radiations may thereby be reduced or eliminated. Filter 27 may be of the dyed plate or interference type or a combination of the two. Filter 27 may be made a component of 28 or 29 as by deposition directly on the front or rear surface of transmitter 28 or on the window of 29, or in any other suitable manner.

In Figure 2 the annular phosphor pattern illustrated may be affixed on face 19 of the cathode ray tube in accordance withknown techniques. It may also be placed in position in accordance with the teachings of my copending application, Serial No. 514,973, filed June 13, 1955. The portion 31 comprises a series of groups of rings; each group containing a plurality of phosphors and is illustrated in greater detail in Figure 3. The pattern of Figure 2 is suited toapplications of the invention wherein an electron beam is deflected radially from the area 33 to the area 35 in repeated motions while defleeting means 15 causes a simultaneous slow rotation of i the thus radially generated spoke. This invention may of course be-applied to rasters other than PPI such as that disclosed in my co-pending application Serial.

No. 448,039, filed August 5, 1954.

In Figure 3 electro-magnetic radiation-emitting index rings 41 are arranged concentrically with respect to lightemitting phosphor 43, 45, and 47. As the electron beam sweeps radially, thereby traversing index rings 41, a series of pulses are generated that constitute the electro-magnetic index signal. As shown in Figure 3 the widths 43, 45, and 47 differ from each other.

An advantage in using groups of rings of individually diilerent, widths is that such variations provide control of the psycho-physical stimuli capable of being impressed upon an observer. For example, a group of phosphors strips45, 47, and 43 that are capable of emitting red, green, and blue light may be used. Strips 45, 47, and 43 are provided with widths which are inversely proportional to the luminous efficiencies of the red, blue, and green phosphors respectively. The phosphors are further selected so that the decay times of the visible output luminescence of the different phosphors are substantially equal. Then under constant electron beam energization, when the beam is swept at substantially constant speed, a white background is presented to the observer.

Modulation of the electron gun current produces a magnitude change of the light output at the face of the cathode ray tube. When the modulation is rapid, so that the change in cathode ray energization of the phosphor pattern occurs while the beam is confined to an individ ual phosphor strip, the color of the, light output at the face of the cathode ray tube will also change. Hence another means of identifying and coding signals is provided. By means of gating circuits, interrogators, doppler radars, etc. it is possible to identify different objects and areas on the face of the tube by color coding. For example, in the case of an airport installation, the PPI presentation may show incoming aircraft reflections as red, outgoing as green; or the radar returns might be color classified according to altitude. The variations in the display, use of the display, and means for generating the display, are many and I again refer to my previously referenced co-pending application for additional details. However it will be understood that the series of electromagnetic index pulses obtained when the cathode ray beam traverses elements 41 are controlled by the characteristics of the material comprising 41, by the spot size of the beam and by the sweep speed. These index pulses are transmitted at the speed of light to collector 2,5. The pulses are then guided to impinge upon detecting means 29. Here the light pulses are converted into electrical voltages or currents, for subsequent, utilization.

In Figure 4, an end view of the neck section 51 of cathode ray tube 11 is illustrated. The radiation-transmitting element 28 is shown in position relative to the pins 21. There is a key 55 at the base of the tube. Rod 28 is sealed to the header at 26. It will be understood that a change is required in the conventional socket into which this assembly plugs to provide clearance for means 28. t

Referring back to Figure 1, the elongated electro-magnetic transmitting element 28 may be divided into. a plurality of segments. One possible division is indicated at 22; another at 24. Only a small quantity of radiation will be lost from the desired transmission loop, or path, when the thus segmented elements comprising 28 are placed close to each other. Many advantages are derived from this type of construction. First, the neck section 51 of the tube need not support the entire length of the radiation transmitter. Second, the external dimensions of the cathodevray tube may more nearly conform to present standards. Third, the choice of materials for the elements of 28 is widened. Those sections external to the tube may be made of Lucite or other material generally not usable in vacuo. Fourth, vibration and shock will be tolerated more readily by the final assembly when space is provided as at 22 and 24 for small movements of the elements comprising 28. And fifth, production capabilities are enhanced by the sub-assembly construction techniques made. possible by segmentation of the radiation transmitter.

In Figure 5, an element. 71, akin to the internally dis. posed portion of 28, of the electro'rnagnetic radiation transmission means is also used to support electrodes 61, 63, 65 of an electron gun. The illustration shows the electrodes crimped mechanically to element 71. ItJWill be understood that other means of alfixing the electrodes to support 71 are available, such as by pinning, and that.

A flat disc-like Window, or a simple lens may be sealed into the neck 51 of the. tube as at 67. This window transmits the radiation from 71 to the means 69. Element 69 transmits the radiation to the desired location external of the tube. As previously mentioned, 69 may be made of Lucite.

The window, or lens, may be made from the same material as 71. In fact, the element 67 may not only be comprised of the same material as the neck 51, thereby eliminating the vacuum seal that otherwise joins 67, to 51, but the neck 51 may be molded or formed with an integral lens as illustrated at 73. The basic require: ment is that 67 be transparent to the wavelength of light being transmitted through it.

The strips 41 suitably include zinc oxide or silver activated zinc-sulphide as the light emitter. Preferably, the radiation from only one of the principle decay components of these phosphors is used in the electro magnetic radiation transmission path. It is to be noted also that a plurality of the combination of elements 67, 69, and 71, may be utilized in combination with a single tube or housing. It is then possible to generate and transmit more than one electro-magnetic signal. In such cases, complete isolation between different electro-magnetic radiation transmitters provides a plurality or independent signal channels. This isolation is accomplished readily by suitable filtering prior to the detecting means of the various electro-magnetic radiations.

It will. be understood that the foregoing description of the invention and the embodiments set forth, are merely illustrative of the principles thereof. Accordingly, the appended claims are to be construed as defining the invention within the full spirit and scope thereof.

I claim:

1. A cathode ray tube comprising: an electron gun, means responsive to excitation by electrons from said gun, said means emitting electro-magnetic radiation as a result of said excitation, said electro-magnetic radiation being in the range extending from infra-red to the ultraviolet, and means within said tube for transmitting at least a part of the said electro-magnetic radiation to a. situs outside the tube, said last means comprising at least one elongated member.

2. A cathode ray tube comprising: an electron gun,

means responsive to excitation by electrons from said gun, said means emitting electro-magnetic radiation in the range, extending from infra-red to waves of ultraviolet radiation as a result of said excitation, and means discrete signal emissive areas arranged in a predetermined geometrical configuration that emit electro-magnetic radiation within the range extending from infrared to ultra-violet as a result of excitation by a beam of energy adapted to scan said radiation emitting means and means positioned within the housing comprising at least one elongated member that pick-up and transmit at least a portion of said radiation to a situs external of said housing.

4. A cathode ray tube comprising: an envelope, an electron gun, means responsive to excitation by electrons from said gun, said means emitting electro-magnetic radiation in the range extending from infra-red to waves of ultra-violet as a result of said excitation, means for transmitting at least a portion of said electromagnetic radiation to a situs outside the tube, said last means comprising an elongated member one end of which is aflixed to said envelope in the vicinity of the electron gun.

5. A cathode ray tube comprising: an envelope, an electron gun, means responsive to excitation by electrons from said gun, said means emitting electro-magnetic radiation in the range extending from infra-red to waves of ultra-violet radiation, as a result of said excitation,

means for transmitting at least a portion of said electromagnetic radiation to a situs outside the tube, said transmitting means comprising an elongated member with one end spaced apart from said envelope.

6. A cathode ray tube in accordance with claim 5 in .which the envelope includes means positioned in align- References Cited in the file of this patent UNITED STATES PATENTS 20 2,720,593 Richards et al Oct. 11, 1955 2,749,449 Bradley et al. June 5, 1956 2,774,908 Wallmark Dec. 18, 1956 

